<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../vue.js"></script>
</head>

<body>
  <div id="app">
    <h1>{{msg}}</h1>
    <button @click = "fn1">累加</button>
    <button @click = "fn2">累减</button>
    <button @click = "fn3($event , 2)">累加2</button>

  </div>
  <script>
    Vue.config.productionTip = false;
    
    const vm = new Vue({
      data() {
        return {
          msg: 1
        }
      },
      methods: {
        fn1(){
          this.msg += 1
        },
        fn2(e){
          console.log(e);
          this.msg += 1
        },
        fn3(e , n){
          console.log(e);
          this.msg += n
        },
      }


    }).$mount("#app")
  </script>
</body>

</html>